Field of the Invention
The present invention relates to an imprint apparatus and an article manufacturing method.
Description of the Related Art
There has been increasing demand for miniaturizing semiconductor devices, MEMSs, and the like, and attention is now paid to conventional photolithography techniques as well as miniaturizing process techniques by which uncured resin on a substrate is molded using a mold to form a resin pattern on the substrate. These techniques are called imprint techniques, by which a several nanometer-order fine structure (pattern) can be formed on a substrate. For example, a photo-curing method is one of the imprint techniques.
In an imprint apparatus that employs the photo-curing method, initially, photo-curing resin (ultraviolet-curing resin) is supplied (coated) to a shot region (imprint region) of a substrate, and this resin (uncured resin) is molded using a mold. Then, light (ultraviolet) is irradiated to cure the resin, the mold is separated (released) from the cured resin on the substrate, and a resin pattern is thereby formed on the substrate.
The substrate to be subjected to imprint process undergoes heating process in a deposition process such as spattering, for example, during the process of manufacturing a device, and accordingly the entire substrate expands or shrinks, and the shape (size) thereof changes in directions of two orthogonal axes in a plane in some cases. Accordingly, in the imprint apparatus, it is necessary, when bringing the resin on the substrate into contact with the mold, to match the shape of a pattern formed on the substrate (substrate pattern) and the shape of a pattern formed on the mold (mold pattern) with each other. The imprint apparatus includes a shape correction mechanism (magnification correction mechanism) that deforms the mold pattern and the substrate pattern by applying external force from a side face of the mold or applying heat to the mold and the substrate, for example.
Now consider the case of applying the imprint apparatus to a manufacturing process of a semiconductor device with about 32 nm half-pitch, for example. In this case, the overlay accuracy is 6.4 nm according to ITRS (International Technology Roadmap for Semiconductors). Accordingly, in order to conform thereto, shape correction also needs to be carried out at an accuracy of several nm or less.
A technique for matching the shape of the substrate pattern and the shape of the mold pattern with each other to improve overlay accuracy is proposed in Japanese Patent Laid-Open No. 2010-080714. With the technique disclosed in Japanese Patent Laid-Open No. 2010-080714, the mold is deformed by a mold chuck that holds the mold to match the substrate pattern and the mold pattern with each other. A technique for performing alignment between the mold and the substrate is also proposed in Japanese Patent Laid-Open No. 2007-137051. With the technique disclosed in Japanese Patent Laid-Open No. 2007-137051, when performing the alignment between the mold and the substrate in a state where the mold is in contact with resin on the substrate, pressure force of the mold against the resin is lowered, thereby facilitating adjustment of a positional relationship between the mold and the substrate.
In the imprint apparatus, as the miniaturization of patterns formed on the substrate advances, the thickness of resin (residual layer) at the time of the imprint process needs to be thinned for an etching process, which is a post-process. Accordingly, when molding the resin, the resin having a thickness of several dozen nm or less is sandwiched between the mold and the substrate. It is known that a liquid held in a small gap with such an order is structured and obtains a large viscoelasticity property.
When the mold and the substrate are relatively moved for alignment in a state where the mold is in contact with the resin on the substrate (i.e., in a state where the resin is sandwiched between the mold and the substrate), force is applied to the mold and the substrate in a direction (shearing direction) parallel with a contact surface, due to the viscoelasticity of the resin. Also, if a foreign particle is sandwiched between the mold and the substrate, the mold and the substrate mesh with each other due to this foreign particle, and force in a direction parallel with the contact surface is applied to the mold and the substrate as in the aforementioned case.
This force in the direction parallel with the contact surface acts as disturbance force during the alignment between the mold and the substrate, and therefore degrades controllability in the alignment between the mold and the substrate. In other words, if force in the direction parallel with the contact surface is generated on the mold and the substrate during the alignment between the mold and the substrate, the accuracy of the alignment between the mold and the substrate lowers, and the time taken for the alignment between the mold and the substrate becomes longer.